2014/08/06 by Christian Hauswald, Pierre Corfdir, Johannes K. Zettler +12 · 1 citation
Engineering · Physics and Astronomy · #Atomic physics #Condensed matter physics #Exciton #GaN-based semiconductor devices and materials #Materials science #Nanowire #Nanowire Synthesis and Applications #Optoelectronics #Physics #Semiconductor Quantum Structures and Devices #Wide-bandgap semiconductor #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.90.165304
published as Phys. Rev. B 90, 165304 (2014) · 10 pages, 5 figures
arxiv created 2014/08/06 · openalex publication_date 2014/10/08 · arxiv updated 2014/10/15 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the origin of the fast recombination dynamics of bound and free excitons in GaN nanowire ensembles by temperature-dependent photoluminescence spectroscopy using both continuous-wave and pulsed excitation. The exciton recombination in the present GaN nanowires is dominated by a nonradiative channel between 10 and 300 K. Furthermore, bound and free excitons in GaN NWs are strongly coupled even at low temperatures resulting in a common lifetime of these states. By solving the rate equations for a coupled two-level system, we show that one cannot, in practice, distinguish whether the nonradiative decay occurs directly via the bound or indirectly via the free state. The nanowire surface and coalescence-induced dislocations appear to be the most obvious candidates for nonradiative defects, and we thus compare the exciton decay times measured for a variety of GaN nanowire ensembles with different surface-to-volume ratio and coalescence degrees. The data are found to exhibit no correlation with either of these parameters, i.e., the dominating nonradiative channel in the GaN nanowires under investigation is neither related to the nanowire surface, nor to coalescence-induced defects. Hence we conclude that nonradiative point defects are the origin of the fast recombination dynamics of excitons in GaN nanowires.